Transposable elements (TEs) sometimes induce karyotypic changes following recombination, breakage and rearrangement. We used
FISH and Southern blot analyses to investigate the amount and distribution of LINE-1 retrotransposons in rodents (genus
Taterillus, Muridae, Gerbillinae) that have recently undergone an important genome repatterning. Our results were interpreted in a known
phylogenetic framework and clearly showed that LINE-1 elements were greatly amplified and non-randomly distributed in the
most rearranged karyotypes. A comparison between FISH and conventional banding patterns provided evidence that LINE-1 insertion
sites and chromosome breakpoints were not strongly correlated, thus suggesting that LINE-1 amplification subsequently accompanied
Taterillus chromosome evolution. Similar patterns are observed in some cases of genomic stresses (hybrid genomes, cancer and DNA-damaged
cells) and usually associated with DNA hypomethylation. We propose that intensively repatterned genomes face transient stress
phases during which some epigenetic features, such as DNA methylation, are relaxed, thus allowing TE amplification.
Key words chromosome - evolution - Mammalia -
Taterillus
- transposable elements